I propose, using a multidisciplinary approach, to investigate the possible origins of social and physiological influence upon reproductive behavior by studying 1) how social and physiological factors influence reproductive activity in reptiles, and 2) how this interaction in turn results in the adaptation of reproductive processes to the ecological and social environments. To this end I intend to use both descriptive and experimental techniques as they might be applied to both the field and laboratory. The present proposal describes studies on the stimulus control of hormone secretion and the endocrine basis of reproductive behavior and physiological processes in reptiles. Of particular interest are the factors underlying the synchronization of male and female reproductive activity in temperate and tropical lizards, the mechanism of action of the male's behavior on female ovarian activity, the sequence and synergy of hormones in the control of male and female sexual behavior, neural and hormonal stimuli underlying coition-induced inhibition of female sexual receptivity, the concentration and pattern of secretion of endogenous hormones during the reproductive cycle, the neural sites of hormone action, and the endocrine control of the sexual refractory period following the breeding season. In addition, field research is planned in which I will investigate variation in species recognition characters, the role of these characters in inter- and intra-specific communication and mate selection, and how these characters have contributed to the origin and maintenance of species difference. I also propose to conduct descriptive studies of the reproductive behavior of sympatric anoles as well as experiments on individual and species recognition, the role of the dewlap in interspecific communication, and display variation. Plans are also made to test in the field hypotheses arising from laboratory work with laboratory populations.